Dynamic configuration and self-tuning on inter-nodal communication resources in a database management system

ABSTRACT

A database management system in which a plurality of nodes form a database instance, each node including a communication manager for dynamically configuring inter-nodal communication resources. The communication manager receives communication resource allocation requests from clients or a self-tuning algorithm. A resource self-tuning mechanism allocates or de-allocates memory blocks used for communication resource elements dynamically in real time without cycling the instance. Memory blocks are de-allocated asynchronously by placing associated communication resource elements in quarantine until all communication resource elements associated with the memory block are quarantined.

CROSS-REFERENCE TO RELATED APPLICATIONS

Under 35 USC § 120, this application is a continuation application andclaims the benefit of priority to U.S. patent application Ser. No.10/410,856, filed Apr. 9, 2003, entitled “Dynamic Configuration andSelf-Tuning of Inter-Nodal Communication Resources in a DatabaseManagement System”, and is related to application Ser. No. 10/421,178,filed on Apr. 22, 2003; application Ser. No. 10/424,201, filed on Apr.25, 2003; and application Ser. No. 11/736,974, filed on Apr. 18, 2007,all of which is incorporated herein by reference.

This application claims benefit under 35 USC 119 of Canadian Application2,383,825 filed on Apr. 24, 2002.

FIELD OF THE INVENTION

The invention relates to database management systems and in particularto dynamic configuration and self-tuning of inter-nodal communicationresources within a database management system.

BACKGROUND OF THE INVENTION

In database management systems such as International Business Machine's(IBM) DB2 Version 7, parameters that govern an amount of inter-nodalcommunication resources cannot be configured dynamically. A user mustestimate values of communication resource parameters with respect toworkloads that will be run against a system prior to starting up aninstance of a database management system. However, if the estimate isnot accurate or the workloads change after the instance has beenstarted, then communication resources can be exhausted, thus preventingthe database management system from servicing certain database requestswithout delay.

When such an event occurs, the user has to either reissue the requestafter other workloads have diminished or force all applications, stopthe database instance, and reconfigure the communication resourceparameters with more optimal values. This is clearly a penalty on theusability and performance of the database management system, becauserecycling the instance and rerunning the workloads are extremelytime-consuming.

In addition, since communication resources can occupy a significantamount of memory space, the user may want to release resources inexchange for memory for other purposes. However, current database enginedesigns require that the instance be stopped and restarted in order forthe new parameter values to take effect.

Prior art solutions that may solve the dynamic configuration problem donot service requests asynchronously or undo asynchronous requestswithout delay. In addition, they do not permit the database server totransparently increase or decrease its communication resources inresponse to fluctuations in communication workload requirements.

There is therefore a need for a database management system that permitsusers to dynamically configure communications resources used by thesystem. There also exists a need for a database management system thatadapts to fluctuations in workloads in a way that is transparent to theuser.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a databasemanagement system that permits a client or an optimization algorithm todynamically configure an amount of memory used for communicationsresources by the system.

It is a further object of the invention to provide a database managementsystem that automatically adapts to fluctuations in workloads in a waythat is transparent to the user.

The invention therefore provides a database management system in which aplurality of nodes form a database instance, each node including acommunication manager for dynamically configuring inter-nodalcommunication resources. The communication manager receivescommunication resource allocation requests from clients or a self-tuningalgorithm. A resource self-tuning mechanism allocates or de-allocatesmemory blocks used for communication resource elements dynamically inreal time without cycling the instance. Memory blocks are de-allocatedasynchronously by placing associated communication resource elements inquarantine until all communication resource elements associated with thememory block are quarantined.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic diagram of a computer network in which aplurality of partitions of a database management system (DB2) aredeployed;

FIG. 2 illustrates a schematic diagram of DB2 server partitions in thedeployment of the DB2 shown in FIG. 1;

FIG. 3 illustrates a schematic diagram of the resource self-tuningmechanism and free resource pool shown in FIG. 2;

FIGS. 4A and 4B are a flowchart of a method in accordance with theinvention for increasing communications resource allocations;

FIGS. 5A and 5B are a flowchart of a first phase of a method inaccordance with the invention for decreasing communications resourceallocations; and

FIG. 6 is a flowchart of a second phase of the method for decreasingcommunications resource allocations.

It will be noted that throughout the appended drawings, like featuresare identified by like reference numerals.

DETAILED DESCRIPTION

The invention therefore provides a database management system in which aplurality of nodes form a database instance. Each node comprises a fastcommunications manager (FCM) for dynamically reconfiguring inter-nodalcommunication resources. The FCM receives requests from clients or theoptimization algorithm to re-allocate communication resources. Aresource self-tuning mechanism maintains a memory descriptor table thatstores a plurality of memory descriptors and a quarantine, forallocating and de-allocating communication resources in response to therequests received from the clients. A free-resource pool storesavailable communication resources.

The invention also provides a system and medium for dynamicallyincreasing communication resources available to the instance of thedatabase. The system and method begin with a step of computing a numberof additional memory blocks required to satisfy the request, thenallocating new memory blocks to support the additional communicationresources. A memory descriptor table is searched for a vacant entry. Thenew memory blocks are allocated and anchored by recording a pointer anda status of the memory block in the vacant entry. The communicationresource elements are created from the new memory blocks and added to afree resource pool to make them available for inter-nodal communicationservices, until all the required additional resources have been created.

The invention also provides a two-phased method for decreasing thecommunication resources available to the instance of the databasemanagement system. In a first phase, the method involves searching forcommunication resource elements that can be de-allocated immediately,and registering those that must be de-allocated asynchronously. A secondphase provides logic for moving a used resource element to a quarantinearea, and de-allocating a memory block when all associated communicationresource elements have been quarantined.

The second phase is invoked whenever a resource element is returned tothe FCM. If the associated memory block is not marked for asynchronousde-allocation, the communication resource element is returned to thefree memory pool. If the associated memory block is marked forasynchronous de-allocation, the associated communication resourceelement is placed in the quarantine.

An embodiment of the invention is described below with reference toInternational Business Machine's (IBM) DB2 Universal Database Manager(UDM) as an example of only one embodiment of a database managementsystem. The invention is applicable to any database management systemthat uses inter-nodal communications resources.

FIG. 1 illustrates a schematic block diagram of a computer network 100having a plurality of server computers 102,110 (only two shown)connected 116,118 to a network 120. The network 120 may be, for example,a local area network (LAN), a wide area network (WAN), a municipal areanetwork (MAN), or an inter-network, such as the Internet. A clientcomputer 124 controlled by a user (not shown) is also connected 122 tothe network 120. Alternatively, the client 124 may be connected (notshown) directly to one of the server computers 102,110. Each servercomputer 102,110 has a respective memory 104,112. The memory 104 of theserver computer 102 has a first DB2 server partition 108, and the memory112 of the server computer 110 has an N^(th) DB2 server partition. Theserver partitions 108,114 are also individually called nodes. The serverpartitions 108,114 are collectively referred to as a database managementsystem instance.

Consequently, the present invention may be implemented as acomputer-implemented system, a computer-implemented method, or acomputer-readable medium storing computer software comprising executableinstructions that, when executed by one or more computers, causes thecomputers to perform the computer-implemented method.

FIG. 2 illustrates a schematic diagram of a DB2 server instance 202 thatincludes the DB2 server partitions 108,114 shown in FIG. 1. The firstDB2 server partition 108 includes a fast communications module 206 (FCM)and higher layers 220 of DB2 server. The FCM 206 has a resourceself-tuning mechanism 208 for dynamically allocating or de-allocatingcommunication resources 210 at a request of a user (not shown). Theresource self-tuning mechanism 208 may also automatically allocatecommunication resources 214, if communication resource elements 214 in afree resource pool 212 begin to run out. The FCM 206 further includes anFCM daemon 218 that uses 217 the communication resource elements 214 tocommunicate 228 with other DB2 server partitions 114. The higher layersof the DB2 server 220 include a DB2 agent 222 that receives clientresource allocation requests 224. The DB2 agent 222 communicates theclient resource allocation requests using messages 216 to the resourcesself-tuning mechanism 208. The N^(th) DB2 server partition 114 isidentical to the first DB2 server partition 108, even though only theFCM 230, FCM daemon 232 and higher layers of the N^(th) DB2 server 234are shown for clarity. The DB2 server partitions 108,114 communicate 204through the network 120 (FIG. 1).

FIG. 3 illustrates a schematic diagram of the resource self-tuningmechanism 208 and free resource pool 212 shown in FIG. 2. The resourceself-tuning mechanism 208 includes a process 302 for returningcommunication resource elements after they are released from use by theFCM daemon 218 (FIG. 2), a memory descriptor table 304, a quarantineindex table 316 and a quarantine area 330. It should be noted that thequarantine index table 316 is a data structure that is, for example,allocated and de-allocated during execution of methods in accordancewith the invention, as described below. The memory descriptor table 304includes a plurality of records, each having a memory descriptor 306, astatus/state information field 308, and a memory pointer field 310. Thestatus/state information field may be set to any one of three differentvalues. The three values respectively represent a status of “USED”,“VACANT” or “ASYNCHRONOUS DE-ALLOCATION”. If the status/stateinformation field 308 is set to “USED” then the respective memorypointer field 310 points to a raw memory block 314, and the memory block314 has been allocated to communication resource elements which may bein the free resource pool 212, or in use by the FCM daemon 218. If thestatus/state information field 308 is set to “VACANT” the respectivememory pointer field 310 is set to a null pointer 315 (this type ofrecord is a null entry, because the memory descriptor table ispreferably a static structure of a predetermined size). If thestatus/state information field 308 is set to “ASYNCHRONOUSDE-ALLOCATION”, the memory block is still held, pending release ofassociated communication resource elements, as will be described belowin some detail. The quarantine area 330 is a collection of communicationresource elements 332 that are associated with memory blocks pendingde-allocation. The quarantine index table 316 includes a plurality ofrecords each having an index field 318, a memory descriptor field 320,that stores a corresponding memory descriptor 306, and a field 322 thatindicates a number of quarantined communication resource elementsassociated with the memory block identified by the memory descriptorfield.

The invention also provides a method for dynamically increasingcommunication resources available to the instance 202 of the DB2. FIGS.4A and 4B are a flowchart 400 of a method for handling a resourceallocation request 224 (FIG. 2) received from a client or from the FCMdaemon 218 to request a dynamic increase in communication resources. Theclient can request a dynamic increase (or decrease) in communicationresources at any time. The FCM daemon 218 can request an increase if itfinds that the free resource pool 212 is empty when it tries to initiatea communications session with another node 206, 230.

The method begins 402 with a step of computing a number of additionalcommunication resource elements required, and the number of memoryblocks that must be allocated to accommodate the communication resourceelements (step 404). The number of communication resource elementsrequired is computed, for example, by subtracting a current number ofexisting communication resource elements from a requested number. As iswell known to persons skilled in the art, each memory block accommodatesa predefined number of communication resource elements, the number beingrelated to the operating system with which the DB2 is instantiated.Whenever a request for increasing communication resources is received,it is possible that the FCM 230 is already involved in a process ofdecreasing the communications resources, because the resourcere-allocation requests can be sent at any time. Consequently, after therequired number of additional resources has been computed, thequarantine is checked to determine if it is empty (step 405).

If the quarantine is empty, a process for decreasing communicationresources, which will be explained below with reference to FIGS. 5A and5B, is not underway. Consequently, the process proceeds to step 406, inwhich the required memory blocks are allocated from a shared memory set.If the shared memory set does not contain enough memory blocks tosatisfy the request, the shared memory set is grown by sending a requestto the operating system, in a manner well known in the art. It isassumed that the shared memory set can always be grown, and in practicethis is almost inevitably true. If for any reason shared memory cannotbe grown, the process cancels and a request denial message (not shown)is returned to the client. Next, the memory descriptor table 304 (step408) is searched for a vacant entry. As noted above, the memorydescriptor table 304 is a table of fixed size and contains at least asmany rows as a maximum number of memory blocks permitted to be used forcommunication resources, as specified in a DB2 configuration file. Instep 410 a one of the new memory blocks is allocated and anchored bycreating a memory pointer that is stored in field 310 of the memorydescriptor table 304. New communication resource elements 214 (FIG. 3)are constructed from the new memory block 314 and added to the freeresource pool 212 to make them available for inter-nodal communicationservices (step 412). In step 414 it is determined whether the requirednumber of new memory blocks 314 have been allocated. If so, the processbranches back to step 408 where a next memory block is allocated,otherwise the process terminates (step 416).

If in step 405, described above, it is determined that the quarantine isnot empty, a process to decrease communication resources is underway.Consequently, the process branches to step 418 (FIG. 4B), where it isdetermined whether the quarantine contains enough communication resourceelements to satisfy the request to increase communication resources. Ifso, the required number of communication resource elements 332 arereleased from the quarantine (step 420). The released communicationresource elements are then added back to the free resource pool 212(step 422), and the status/state information field 308 in the memorydescriptor table 304 for the corresponding memory blocks are changedfrom “ASYNCHRONOUS DE-ALLOCATION” to “USED” to indicate that the memoryblocks are no longer to be de-allocated (step 424). In step 426 thequarantine is checked again to determine whether it is empty subsequentto the release performed in step 420. If the quarantine is empty, theprocess branches to connector “F” (FIG. 4A) at 432 and terminates. Ifthe quarantine is not empty, there was a de-allocation request inprogress that requested a larger decrease than the increase justperformed. Consequently, the quarantine 330 is cleaned up by immediatelyde-allocating remaining communication resource elements 332 that thequarantine contains (step 428), and the corresponding entries in thememory descriptor table 304 are marked as “VACANT”. The process thenbranches to connector “F” (FIG. 4A) at 432, and terminates.

If in step 418 it is determined that the quarantine 330 does not containsufficient communication resource elements 214 to satisfy the request,all of the quarantined communication resource elements are released(step 436). The memory descriptor table 304 is then modified to changethe status/state information 308 related to the corresponding entriesfrom “SYNCHRONOUS DE-ALLOCATION” to “USED” (step 438). The releasedcommunication resource elements are then returned to the free resourcepool 212 (step 440). The number of additional communication resourcesrequired is then computed by subtracting the number released from thequarantine in step 436 from the total number computed in step 404, andthe process branches back to connector “E” (FIG. 4A) at 444, where theprocess continues as explained above.

The method and system in accordance with the invention also permits aclient to request that communications resources be de-allocated(decreased). Depending on the usage level of the communication resourcesat the time that the client request 224 is received, a sufficient numberof free communication resource elements 214 might not be available forimmediate de-allocation to satisfy the request. It can potentially takea long time before adequate free communication resource elements becomeavailable to satisfy the de-allocation request 224. To avoid blockingthe database management instance 202 from performing other tasks whilethe dynamic configuration request 224 is being serviced, the inventionprovides an asynchronous mechanism to handle dynamic de-allocationrequests.

The invention provides a two-phased method for decreasing thecommunication resources available to the instance 202 of the databasemanagement system. A first phase of the method involves searching formemory blocks that can be de-allocated immediately, and registeringthose that must be de-allocated asynchronously. A second phase provideslogic for moving a used communication resource element to a quarantinearea, and performing garbage collection. The second phase is invokedwhenever a communication resource element is returned to the FCM 206.

Since the process of locating and identifying memory blocks forimmediate and asynchronous de-allocation can be computationally complex,the first phase of the method is optimized using the quarantine index(QI) table 316 (FIG. 3).

FIGS. 5A and 5B are a flowchart 500 for implementing the first phase ofprocessing a request to decrease communication resources dynamically.The method starts 502 by computing a number of memory blocks to bede-allocated (step 504), using methods described above. Then memoryspace for a QI table 316 is allocated, if required, and the QI table 316is initialized, if required (step 506). All the free communicationresource elements 214 in the free resource pool 212 are resolved intoquarantine area 330, and the QI table 316 is correspondingly updated(step 508). The QI table 316 is then sorted according to the number ofquarantined communication resource elements for each memory descriptor(step 510). If it is determined (step 512) that the required number ofmemory blocks have not been de-allocated, the process advances to step522 (FIG. 5B), which is described below. Otherwise, the QI table 316 isde-allocated, if required (step 514). The free resource pool 212 is thenreconstructed from the elements 332 in the quarantine area 330 that arenot marked for asynchronous de-allocation (step 516) and the processfinishes (step 520).

If the QI table 316 indicates that more memory blocks cannot bede-allocated immediately (step 522) the process moves to step 528,described below. Otherwise, using the sorted QI table 316, a memoryblock for immediate de-allocation is located (step 524). The memoryblock can be immediately de-allocated if the number of quarantinedcommunication resource elements 332, which is recorded in column 322 ofthe quarantine index table 316 is equal to the total number ofcommunication resource elements that can be created using the raw memoryblock. The memory block is de-allocated and the correspondingstatus/state information entry 308 in the memory descriptor table 304 ischanged to “VACANT” (step 526). Thereafter, the process returns to step512.

If the process branched from step 522 to step 528, as explained above,it is determined in step 528 whether all of the required memory blocks314 are marked for asynchronous de-allocation. If so, the processreturns to step 514 (FIG. 5A). Otherwise, using the sorted QI table 316,a memory block with the highest number of quarantined communicationresource elements 332 is located and marked for asynchronousde-allocation in the memory descriptor table 304. Steps 528,530 arerepeated until all memory blocks in the QI table 316 are marked forasynchronous de-allocation.

FIG. 6 shows a flowchart 600 of the second phase of the method forresponding to a request to decrease communication resources dynamically.The method starts 602 with a step of indexing into the memory descriptortable 304 using the memory descriptor of a returning communicationresource elements 302 (step 603). It is then determined (step 604)whether the memory block associated with the returning communicationresource element 302 in the memory descriptor table 304 has itsstatus/state information 308 set to “ASYNCHRONOUS DE-ALLOCATION”. If itdoes not, it is recycled to the free resource pool 212 (step 606) andthe process finishes (step 614). Otherwise, the communication resourceelement 302 is placed in the quarantine area 330 (step 608). If it isdetermined in step 610 that the quarantine area 330 is full, or apredetermined quarantine threshold has been exceeded, garbage collectionis performed to de-allocate any memory blocks that can be immediatelyde-allocated (step 612) because all associated communication resourceelements have been returned to the quarantine. In either case, theprocess ends at 614.

Self-tuning of communication resources in adaptation to user workloadsemploys the method described above with reference to FIGS. 4, 5 and 6.The methods are invoked when the FCM component detects that resourceshave fallen below or risen above self-diagnosed thresholds, which arestatically or dynamically established using specified or computedconfiguration parameters.

An advantage of the invention is that it permits clients to adjustinter-nodal communication resources, in an asynchronous fashion, withouthaving to stop all applications and recycle the instance 202. Inaddition, because of the memory descriptor table 304 and the quarantinearea 330, users can submit new requests 224 to adjust the resourcesimmediately even when there is a request pending completion (which couldtake a long time). The FCM 206 does not have to wait for a backgroundrequest to be finished before servicing a new request. Advantageously,this permits users to undo submitted requests immediately. As well, theinvention provides a database management system's inter-nodalcommunication component with an ability to self-tune its communicationresources in adaptation to workload requirements, without affectingrunning applications or requiring manual intervention by a databaseadministrator.

The embodiment(s) of the invention described above is intended to beexemplary only. The scope of the invention is therefore intended to belimited solely by the scope of the appended claims.

1. A database management system for configuring communication resourcesthat includes a plurality of nodes in a database instance executed byone or more computers, comprising: a communication manager on each node,and executed by a computer, for receiving one of a communicationresource reconfiguration request at one of a plurality of serverpartitions that forms a database management system (DBMS) serverinstance, the communication resource configuration request beingreceived from one of: a client in the system, another server partitionin the DBMS server instance, and a daemon in the one server partition;the communications manager responsive to the communication resourceconfiguration request to: dynamically configure a number ofcommunication resource elements initialized in the one server partitionfor communication with one or more other server partitions in the DBMSserver instance to satisfy the communication resource configurationrequest, dynamic configuration of the number of communication resourceelements initialized in the one server partition being accomplished inreal-time without having to stop and restart the DBMS server instance;and, dynamically configure a number of communication resource elementsinitialized in the one server partition for communication with one ormore other server partitions in the DBMS server instance to satisfy thecommunication resource configuration request, dynamic configuration ofthe number of communication resource elements initialized in the oneserver partition being accomplished in real-time without having to stopand restart the DBMS server instance; and a communication daemon of thecommunication manager communicating the communication resourceconfiguration request to at least one other server partition in the DBMSserver instance using one or more communication resource elementsinitialized in the one server partition, wherein the communicationresource configuration request received by the one server partition is arequest to increase communication resources and dynamically configuringthe number of communication resource elements initialized in the oneserver partition comprises: computing a number of communication resourceelements that needs to be initialized to satisfy the request to increasecommunication resources; computing a number of memory blocks that needsto be allocated to accommodate the number of communication resourceelements needed, each memory block accommodating a predefined number ofcommunication resource elements; determining whether there are anycommunication resource elements in a quarantine area of the one serverpartition; and responsive to there being no communication resourceelement in the quarantine area of the one server partition, allocatingthe number of memory blocks needed from a shared memory set of thecomputer on which the one server partition is located, and initializingthe number of communication resource elements needed from the memoryblocks allocated from the shared memory set of the computer on which theone server partition is located, wherein responsive to there being oneor more communication resource elements in the quarantine area of theone server partition, the one or more communication resource elements inthe quarantine area being associated with one or more memory blocksmarked for dynamic de- allocation, dynamically configuring the number ofcommunication resource elements initialized in the one server partitionfurther comprises: determining whether a number of communicationresource elements in the quarantine area is greater than or equal to thenumber of communication resource elements needed; responsive to thenumber of communication resource elements in the quarantine area beinggreater than or equal to the number of communication resource elementsneeded, releasing the number of communication resource elements neededfrom the quarantine area, and returning the communication resourceelements released from the quarantine area to a free resource pool ofthe one server partition, wherein responsive to the number ofcommunication resource elements in the quarantine area being less thanthe number of communication resource elements needed, dynamicallyconfiguring the number of communication resource elements initialized inthe one server partition further comprises: releasing all communicationresource elements in the quarantine area; returning all communicationresource elements released from the quarantine area to the free resourcepool of the one server partition; computing a number of additionalcommunication resource elements that still needs to be initialized tosatisfy the request to increase communication resources; computing anumber of additional memory blocks that still needs to be allocated toaccommodate the number of additional communication resource elementsstill needed; allocating the number of additional memory blocks stillneeded from the shared memory set of the computer on which the oneserver partition is located; and initializing the number of additionalcommunication resource elements still needed from the additional memoryblocks allocated from the shared memory set of the computer on which theone server partition is located.
 2. A database management system forconfiguring communication resources that includes a plurality of nodesin a database instance executed by one or more computers, comprising: acommunication manager on each node, and executed by a computer, forreceiving one of a communication resource reconfiguration request at oneof a plurality of server partitions that forms a database managementsystem (DBMS) server instance, the communication resource configurationrequest being received from one of: a client in the system, anotherserver partition in the DBMS server instance, and a daemon in the oneserver partition; the communications manager responsive to thecommunication resource configuration request for: dynamicallyconfiguring a number of communication resource elements initialized inthe one server partition for communication with one or more other serverpartitions in the DBMS server instance to satisfy the communicationresource configuration request, dynamic configuration of the number ofcommunication resource elements initialized in the one server partitionbeing accomplished in real-time without having to stop and restart theDBMS server instance; and a communication daemon of the communicationmanager communicating the communication resource configuration requestto at least one other server partition in the DBMS server instance usingone or more communication resource elements initialized in the oneserver partition, wherein the communication resource configurationrequest received by the one server partition is a request to decreasecommunication resources and dynamically configuring the number ofcommunication resource elements initialized in the one server partitioncomprises: computing a number of memory blocks that needs to bede-allocated to satisfy the request to decrease communication resources;resolving all communication resource elements in a free resource pool ofthe one server partition to a quarantine area of the one serverpartition; de-allocating each memory block in which all communicationresource elements associated with the memory block are resolved in thequarantine area; determining whether the number of memory blocks thatneeds to be de-allocated has been de-allocated; and responsive to thenumber of memory blocks that needs to be de-allocated having been de-allocated, returning all communication resource elements that are notassociated with a memory block marked for dynamic de-allocation from thequarantine area of the one server partition to the free resource pool ofthe one server partition, wherein responsive to the number of memoryblocks that needs to be de-allocated not having been de-allocated,dynamically configuring the number of communication resource elementsinitialized in the one server partition further comprises: computing anumber of additional memory blocks that still needs to be de allocatedto satisfy the request to decrease communication resources; determiningwhether any memory blocks have been marked for dynamic de allocation;and responsive to no memory block having been marked for dynamicde-allocation, marking one or more memory blocks for dynamicde-allocation, a number of memory blocks marked for dynamicde-allocation being equal to the number of additional memory blocksstill needed, each memory block marked for dynamic de-allocation beingselected based on a number of communication resource elements associatedwith the memory block that is resolved in the quarantine area of the oneserver partition, and returning all communication resource elements thatare not associated with a memory block marked for dynamic de-allocationfrom the quarantine area of the one server partition to the freeresource pool of the one server partition, wherein responsive to one ormore memory blocks having been marked for dynamic de-allocation,dynamically configuring the number of communication resource elementsinitialized in the one server partition further comprises: determiningwhether a number of memory blocks marked for dynamic de-allocation isgreater than or equal to the number of additional memory blocks stillneeded; responsive to the number of memory blocks marked for dynamicde-allocation being greater than or equal to the number of additionalmemory blocks still needed, returning all communication resourceelements that are not associated with a memory block marked for dynamicde-allocation from the quarantine area of the one server partition tothe free resource pool of the one server partition.
 3. The system ofclaim 2, wherein responsive to the number of memory blocks marked fordynamic de-allocation being less than the number of additional memoryblocks still needed, dynamically configuring the number of communicationresource elements initialized in the one server partition furthercomprises: computing a number of memory blocks that further needs to bede-allocated to satisfy the request to decrease communication resources;marking one or more memory blocks for dynamic de-allocation, a number ofmemory blocks marked for dynamic de-allocation being equal to the numberof memory blocks further needed, each memory block marked for dynamicde-allocation being selected based on a number of communication resourceelements associated with the memory block that is resolved in thequarantine area of the one server partition; and returning allcommunication resource elements that are not associated with a memoryblock marked for dynamic de-allocation from the quarantine area of theone server partition to the free resource pool of the one serverpartition.
 4. A medium storing computer software for configuringcommunication resources in database management systems, the computersoftware, when executed by one or more computers, causes the computer toperform a method comprising: receiving a communication resourceconfiguration request at a communications manager executed by a computerfor one of a plurality of server partitions that forms a databasemanagement system (DBMS) server instance, the communication resourceconfiguration request being received from one of: a client in thesystem, another server partition in the DBMS server instance, and adaemon in the one server partition; the communications managerresponsive to the communication resource configuration request for:dynamically configuring a number of communication resource elementsinitialized in the one server partition for communication with one ormore other server partitions in the DBMS server instance to satisfy thecommunication resource configuration request, dynamic configuration ofthe number of communication resource elements initialized in the oneserver partition being accomplished in real-time without having to stopand restart the DBMS server instance; and communicating thecommunication resource configuration request to at least one otherserver partition in the DBMS server instance using one or morecommunication resource elements initialized in the one server partition,wherein the communication resource configuration request received by thecommunications manager on one server partition is a request to increasecommunication resources and dynamically configuring the number ofcommunication resource elements initialized in the one server partitioncomprises: computing a number of communication resource elements thatneeds to be initialized to satisfy the request to increase communicationresources; computing a number of memory blocks that needs to beallocated to accommodate the number of communication resource elementsneeded, each memory block accommodating a predefined number ofcommunication resource elements; determining whether there are anycommunication resource elements in a quarantine area of the one serverpartition; and responsive to there being no communication resourceelement in the quarantine area of the one server partition, allocatingthe number of memory blocks needed from a shared memory set of thecomputer on which the one sewer partition is located, and initializingthe number of communication resource elements needed from the memoryblocks allocated from the shared memory set of the computer on which theone server partition is located, wherein responsive to there being oneor more communication resource elements in the quarantine area of theone server partition, the one or more communication resource elements inthe quarantine area being associated with one or more memory blocksmarked for dynamic de- allocation, dynamically configuring the number ofcommunication resource elements initialized in the one server partitionfurther comprises: determining whether a number of communicationresource elements in the quarantine area is greater than or equal to thenumber of communication resource elements needed; responsive to thenumber of communication resource elements in the quarantine area beinggreater than or equal to the number of communication resource elementsneeded, releasing the number of communication resource elements neededfrom the quarantine area, and returning the communication resourceelements released from the quarantine area to a free resource pool ofthe one sewer partition, wherein responsive to the number ofcommunication resource elements in the quarantine area being less thanthe number of communication resource elements needed, dynamicallyconfiguring the number of communication resource elements initialized inthe one server partition further comprises: releasing all communicationresource elements in the quarantine area; returning all communicationresource elements released from the quarantine area to the free resourcepool of the one sewer partition; computing a number of additionalcommunication resource elements that still needs to be initialized tosatisfy the request to increase communication resources; computing anumber of additional memory blocks that still needs to be allocated toaccommodate the number of additional communication resource elementsstill needed; allocating the number of additional memory blocks stillneeded from the shared memory set of the computer on which the oneserver partition is located; and initializing the number of additionalcommunication resource elements still needed from the additional memoryblocks allocated from the shared memory set of the computer on which theone server partition is located.
 5. A medium storing computer softwarefor configuring communication resources in database management systems,the computer software, when executed by one or more computers, causesthe computer to perform a method comprising: receiving a communicationresource configuration request at a communications manager executed by acomputer for one of a plurality of server partitions that forms adatabase management system (DBMS) server instance, the communicationresource configuration request being received from one of: a client inthe system, another server partition in the DBMS server instance, and adaemon in the one server partition; the communications managerresponsive to the communication resource configuration request for:dynamically configuring a number of communication resource elementsinitialized in the one server partition for communication with one ormore other server partitions in the DBMS server instance to satisfy thecommunication resource configuration request, dynamic configuration ofthe number of communication resource elements initialized in the oneserver partition being accomplished in real-time without having to stopand restart the DBMS server instance; and communicating thecommunication resource configuration request to at least one otherserver partition in the DBMS server instance using one or morecommunication resource elements initialized in the one server partition,wherein the communication resource configuration request received by theone server partition is a request to decrease communication resourcesand dynamically configuring the number of communication resourceelements initialized in the one server partition comprises: computing anumber of memory blocks that needs to be de-allocated to satisfy therequest to decrease communication resources; resolving all communicationresource elements in a free resource pool of the one server partition toa quarantine area of the one server partition; de-allocating each memoryblock in which all communication resource elements associated with thememory block are resolved in the quarantine area; determining whetherthe number of memory blocks that needs to be de-allocated has beende-allocated; and responsive to the number of memory blocks that needsto be de-allocated having been de- allocated, returning allcommunication resource elements that are not associated with a memoryblock marked for dynamic de-allocation from the quarantine area of theone server partition to the free resource pool of the one serverpartition, wherein responsive to the number of memory blocks that needsto be de-allocated not having been de-allocated, dynamically configuringthe number of communication resource elements initialized in the oneserver partition further comprises: computing a number of additionalmemory blocks that still needs to be de allocated to satisfy the requestto decrease communication resources; determining whether any memoryblocks have been marked for dynamic de-allocation; and responsive to nomemory block having been marked for dynamic de-allocation, marking oneor more memory blocks for dynamic de-allocation, a number of memoryblocks marked for dynamic de-allocation being equal to the number ofadditional memory blocks still needed, each memory block marked fordynamic de-allocation being selected based on a number of communicationresource elements associated with the memory block that is resolved inthe quarantine area of the one server partition, and returning allcommunication resource elements that are not associated with a memoryblock marked for dynamic de-allocation from the quarantine area of theone server partition to the free resource pool of the one serverpartition, wherein responsive to one or more memory blocks having beenmarked for dynamic de-allocation, dynamically configuring the number ofcommunication resource elements initialized in the one server partitionfurther comprises: determining whether a number of memory blocks markedfor dynamic de-allocation is greater than or equal to the number ofadditional memory blocks still needed; responsive to the number ofmemory blocks marked for dynamic de-allocation being greater than orequal to the number of additional memory blocks still needed, returningall communication resource elements that are not associated with amemory block marked for dynamic de-allocation from the quarantine areaof the one server partition to the free resource pool of the one serverpartition.
 6. The medium of claim 5, wherein responsive to the number ofmemory blocks marked for dynamic de-allocation being less than thenumber of additional memory blocks still needed, dynamically configuringthe number of communication resource elements initialized in the oneserver partition further comprises: computing a number of memory blocksthat further needs to be de-allocated to satisfy the request to decreasecommunication resources; marking one or more memory blocks for dynamicde-allocation, a number of memory blocks marked for dynamicde-allocation being equal to the number of memory blocks further needed,each memory block marked for dynamic de-allocation being selected basedon a number of communication resource elements associated with thememory block that is resolved in the quarantine area of the one serverpartition; and returning all communication resource elements that arenot associated with a memory block marked for dynamic de-allocation fromthe quarantine area of the one server partition to the free resourcepool of the one server partition.